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Schematic Design of an Accelerated Bridge Construction Project Michael P. Culmo, P.E. Vice President of Transportation and Structures CME Associates, Inc., East Hartford, CT Reference Manual • Use the Connections Details Manual – Type study concept – Select details from various states Case Scenario • 4 lane bridge over an expressway • Existing bridge has deteriorated beyond repair • Heavy traffic on both roadways • There is a short but undesirable detour Public Involvement • Public hearing held • Businesses do not want a long construction process with stage construction • Businesses are not keen about a detour • They will accept a short term closure with the detour – As opposed to a long term staged project Design Approach Options • Build a temporary bridge to speed up construction of the new bridge – $$$$ – Not that fast • Use multi-stage construction – Very long construction – Will require long term lane closures • Establish the detour and accelerate the bridge construction to less than 30 days Existing Bridge Existing bridge issues Deck Joints Low Clearance Proposed Bridge Type • After a formal type study, the owner opted with the following structure criteria – Use NEXT Beams to accelerate construction • Design as simple span for Dead Load and continuous spans for Live Load – – – – Increase clearance by raising approach grades (3’) Use integral abutments (no deck joints) Composite concrete deck Membrane waterproofing and Bituminous wearing surface – Use Precast Rail System • (Vermont/NH system) Substructures • Push abutments back to top of slope – Minimize wingwall requirements – Use integral abutments with flying wings – Eliminate spray attack on abutments • Place abutments in a different footprint than the existing – facilitates construction • Use open frame pier bent on spread footings Proposed Bridge Move abutment away from roadway No Deck joints Increase vertical clearance Bridge Section Beam Design • Preliminary Beam Sizing – Use PCI NEXT Beam Standards Beam Design • LLDF Beam Design • AASHTO LL Distribution Factor – Type K Moment Shear Beam Design • AASHTO LLDF Type H Shear Moment Beam Design Structure Type H K LLDF Moment 0.96 0.752 LLDF Shear 1.17 0.938 How to select details FHWA manual “Connection details for prefabricated bridge elements and systems” 1. Review Chapter 1 • Investigate connection types, materials, tolerances 2. Search applicable sections of other chapters for details Section 1.4 Typical Connection Types • After reviewing chapter 1, the owner chose the following connection types – Grouted reinforcing splice couplers • Quick, proven system • Can develop full bar strength • Simplifies the design process (similar to CIP) – Grouted Voids • Easy for simple connections – Concrete Closure pours between precast elements • Use for a limited number of connections (slower) Grouted Reinforcing Splice Connectors • Emulates a reinforcing steel lap splice • Multiple companies – non-proprietary • Used in precast parking garages and stadiums and bridges Grouted Reinforcing Splice Connectors • Emulates a reinforcing steel lap splice • Multiple companies – nonproprietary • Used in precast parking garages and stadiums and bridges • Time Lapse Video on YoutubeTM – Search “Georgia Pier Construction” • Installation Video on YoutubeTM Search “Georgia Pier Construction” Installation video Footing to Sub-grade Connection Footing Details Footing to Column Connection Footing to Column Connection Column to Cap Connection Column to Cap Connection Completed Pier Column to cap connection Column to footing connection Footing to subgrade connection Abutment Details • Integral Abutment to precast piles – Section 3.2.3.1 Precast Integral Abutment to Piles • Detail developed by Maine DOT – Used on three different bridges Abutment to Pile Connection Abutment to Pile Connection Abutment To Wingwall Connection Abutment To Wingwall Connection Approach Slab Connection Completed Abutment Approach slab connection Flying Wingwall connection Abutment cap connection Pile to cap connection Deck Design with Next Beam • Design as a conventional cast in place deck – Use max stem spacing for design (5.0 feet) – Design overhang from outside stem (2.53 feet) Parapet Connection Parapet Connection Superstructure to Integral Abutment Connection Use a similar detail at the pier Composite Deck Membrane waterproofing with bit. Wearing surface Precast Parapet Completed Bridge Precast Pier Precast Integral Abutment Final Bridge Estimated Construction Schedule Costs • Typical New Bridge (Cost=$200/sf) = $1,920,000 • Premium for ABC (assume 20%) = $384,000 • Temporary Bridge (Cost=$60/sf) = ($576,000) Net Savings = Note: These prices will vary by region $192,000 Other Cost Savings • Ways to reduce bid prices with ABC • • • • • Standardization Programmatic (not one of a kind) Reduced project site costs (trailers, etc.) Reduced Maintenance of Traffic Costs Inflation • Other Non- Bid Savings with ABC • Fewer Police Details • Reduced Resident Engineering time • User Costs • Plus: $$ Can be significant • Minus: $$ Not in the budget Quality • Florida has had very good success with precast piers in very harsh environments • Precast concrete beams require no maintenance • Integral abutments eliminate deck joints Old Adage You can only have any two High Quality Rapid Construction Low Cost By elimination of temporary bridges or costly stage construction schemes, you CAN have all three Conclusions • It is possible to build a complete bridge in 30 days (or less) • The FHWA manual provides a starting point for a complete bridge prefabrication project • You do not need to sacrifice quality to get rapid construction • You can save money on an accelerated bridge project by: – Reducing construction time – Eliminate temporary bridges or staging Questions [email protected]